CHAPTER 9
FLUID SERVICING AND SUPPORT EQUIPMENT
INTRODUCTION
the fluid to open air or to other atmospheric
contamination. The unit accepts the standard, 1-gallon
Fluid servicing consists of adding new filtered
container, which, when installed, serves as a reservoir.
hydraulic fluid to a system, which replaces fluid lost
The servicing unit has 3-micron (absolute) filtration to
through leakage, system maintenance, or malfunction.
prevent particulate contamination of a system by new
The type of support equipment varies, depending on
fluid that may not meet the prescribed cleanliness prior
the type of aircraft. As an AM, you must know this
to packaging. Contamination in new fluid is rare, but it
equipment and how to operate it. Hydraulic support
does occur.
equipment (SE) is used to service and test hydraulic
The original fluid container serves as a reservoir
systems and components. To use the equipment, you
for the H-250-1 servicing unit. This container is not
must understand each piece of hydraulic SE so you can
opened until it is placed in the unit, and the handle
maintain aircraft hydraulic systems. The maintenance
assembly pressed into a locked position. When the
and operation of specific SE units are described in
handle is locked, the can is sealed into the unit by
applicable manufacturer's operation and service
cleanly piercing its top and bottom. This action
instructions manual (listed in the Naval Aeronautical
automatically destroys the can's potential for reuse.
Publications Index (NAPI), under "Test Equipment,"
The H-250-1 servicing unit is equipped with a
17 series group), and in the maintenance instructions
top-piercing pin, which is drilled to provide the can
peculiar to the specific aircraft.
with atmospheric venting through a 5-micron filter.
Also, it has a check valve to minimize airborne
FLUID SERVICING EQUIPMENT
particulate and moisture contamination. The lower
piercing pin is drilled so the hydraulic fluid can reach
LEARNING OBJECTIVE: Identify the
the pump through a passage in the base casting and a
support equipment used to service and test
3-micron filter. The filter is a nonbypass type. When it
aircraft hydraulic systems and components.
becomes loaded, the unit is inoperative. The filter
housing is designed so that the pump won't operate if a
All maintenance levels use support equipment
filter element has not been installed.
(SE). General types of hydraulic SE are hydraulic fluid
A pressure gauge, an air trap, and a manual air
dispensing equipment, portable hydraulic test stands,
bleed valve are attached directly to the pump assembly
and stationary hydraulic test stands.
base. The air trap automatically removes any air
HYDRAULIC FLUID DISPENSING
present in the fluid at the pump chamber and retains it
EQUIPMENT
in a separate trap. Air collected in the trap is vented
from the unit by manually operating a spring-loaded,
Hydraulic fluid dispensing units are portable.
air bleed valve.
They are used to replenish hydraulic fluid lost or
The H-250-1 servicing unit has an 8-foot service
otherwise removed from a system. They provide a
hose that is equipped with a 3-micron, in-line filter
means of dispensing new filtered fluid under pressure
connected at the discharge end, which prevents reverse
in a manner that minimizes the introduction of external
flow contamination through the hose. There are
contaminants. Several different types of hydraulic
several types of disconnect fittings on the reservoir
fluid dispensing equipment are available.
service units of naval aircraft. There are no mating
fittings provided with the unit. Each activity must
Model H-250-1 Hydraulic Servicing Unit
procure and install the disconnect fitting required for
compatibility with the aircraft supported. Both male
The Model H-250-1 hydraulic servicing unit is a
and female fittings are procured so that half can be
1-gallon servicing unit (fig. 9-1). It provides a way of
installed on the hose end and half on the bracket
servicing systems by hand-pumping filtered fluid
provided. The bracket-mounted fittings will provide a
directly from the original container without exposing
9-1
